Advances in Food Science and Engineering

7

Authors: Agidi Gbabo, Andrew N. Efomah, Gana Ibrahim Mohammed

A steam heated platform dryer with a capacity of 4 tons per day was designed and fabricated in Desfabeng Company Nigeria limited, Bida, Niger State, Nigeria. The system is made up of the following components; a boiler, pressure relief valve, drain valve, drying bed, furnace and heat exchangers pipes. Evaluation of the system was carried by comparing its performance with the direct sundry method. The results of the testing revealed that the steam heated platform dryer showed a uniform drying rate and a limited drying time of two hours for 335kg of parboiled paddy with a head rice recovery of 90% and a moisture removal rate of 16kg/hr. While for the sundried method a moisture content of 22% (wb), moisture removal rate of 8kg/hr and head rice recovery of 50% was obtained. The dryer was found to be very easy to operate and maintain due to its simple design.

13

Authors: P. R. Davara, A. K. Varshney, V. A. Naliapara, V. P. Sangani

Raw juice of prickly pear is viscous and turbid in nature. The clarity of such juice can be improved through enzymatic clarification. An experiment was conducted to standardize the process parameters for clarification of prickly pear juice using pectinase enzyme. Experiment was designed according to response surface methodology (RSM) by keeping three selected independnt variables at five different levels, i.e. enzyme concentrations (0.01, 0.026, 0.050, 0.074 and 0.09%), incubation temperatures (40, 44, 50, 56 and 60 °C), and incubation time (60, 84, 120, 156 and 180 min). Second order central composite rotatable design was employed to study the effect of enzymatic treatments on yield, viscosity, clarity, and turbidity of juice. Response surface modeling showed that the generated regression models were adequate to explain the data variation as well as the the actual relationship between independent variables and responses. The coefficient of determination, R2 values for all the selected parameters were greater than 0.9. Through response surface analysis, the optimum conditions for enzymatic clarification of prickly pear juice were established as 0.056% enzyme concentration, 47 °C incubation temperature, and 155 min incubation time. This interaction of process parameteres was able to improve the yield by up to 88.83% and clarity up to 52.86% as well as decreasing the viscosity by up to 1.60 cP, and turbidity by up to 123.02 NTU.

9

Authors: María Luisa Pérez-Rodríguez, Rebeca López-Froilán, Ángela Casado

Thirty two samples of flavored water commercialized in Spain were evaluated for their antioxidant capacities by three methods: AOP based in cupric ion reducing antioxidant capacity (CUPRAC), free radical scavenging capacity by N,N-dimethyl-p-phenylenediamine (DMPD), and total polyphenols content performed by Folin-Ciocalteu reagent. Flavored waters are a kind of soft drinks formulated with mineral or bottled water, flavorings (extracts, juices or aromas) and additives which mainly are acidifying agents and sweeteners. The samples were distinguished in three groups in function of the ingredient that provide the flavor. The antioxidant capacity was higher in waters with plant extracts followed by those with aromas and finally by waters with a small amount of juices. In spite of the low antioxidant capacity, regular use of flavored water could contribute substantially to the total of dietary antioxidants. This kind of drinks does not contain alcohol or stimulants and neither typically contain sugar. This represents a certain advantage over traditional soft drinks.

11

Authors: P. R. Davara, M. N. Dabhi, P. J. Rathod, Heena Bhatu

Extraction of pectin from Kesar mango peel, a waste from mango canning and food processing industries, was carried out using cation exchange resin as an extracting medium. The effect of peel to extracting medium ratio and extraction temperature on yield and recovery of pectin was studied. Cation exchange resin was found to be the best extracting medium for extraction of pectin from mango peels. Maximum yield of pectin was obtained by taking two extractions each for one-hour duration employing a peel to extracting medium ratio of 1:4 (w:w), extraction temperature of 80 °C and at pH of 2.56. Using the optimum extracting conditions, about 14.78% (DWB) of purified pectin was obtained from mango peels which gave the recovery of 96.32%. The jelly grade of the pectin was found to be 170 at the optimized condition.